Lapping tool



June 5, 1962 J. G. KAVENY ETAL 3 LAPPING TOOL Filed Nov. 19, 1959 2 Sheets-Sheet 1 June 5, 1962 J, 3. KAVENY ETAL 3,037,328

LAPPING TOOL Filed Nov. 19, 1959 2 Sheets-Sheet 2 United States Patent 3,037,328 TLAPPKNG 1500i.

John Gordon Kaveny, Montclair, and Gustav Peterson, Bloomfield, Null, assignors to Dyirrex Corporation, Montclair, N.J., a corporation of New Jersey Filed Nov. 19, 1959, Ser. No. 854,139 4 tjlairns. (Cl. 51-34) This invention relates to lapping machines. More particularly, it relates to lapping machines having a lapping tool mounted on a spindle, whereby the lapping action is provided by rotating the lapping tool while holding it in engagement with a work piece.

Spindle mounted lapping tools are employed to lap the apertures of wire drawing dies, bushings and the like, and it has been proposed and practiced to impart to the tool a reciprocating motion as well as a rotary motion. The dual character of the tool motion necessitates complication of the spindle driving mechanism and of the manner in which the spindle is mounted. Since the lapping action results in the dispersion of dust particles of highly abrasive material, in machines where the action of the spindle is complicated and the moving parts of the spindle assembly more numerous, it becomes more important to provide suitable means for protectingthe spindle assembly mechanism from the injurious action of abrasive particles. Accordingly, it is a principal object of the invention to provide improved means for protecting certain of the spindle assembly parts from attack by dust as is commonly present in the environment of the lapping machine.

Another problem which confronts the art is provision of versatility in the lapping machines, particularly versatility with respect to lapping of work pieces having tapered apertures. Wire drawing dies commonly have tapered apertures, and as between dies for different services, the taper or degree of inclination with respect to the aperture axis, and also the size of the aperture varies to an extent such that lapping machines commonly used heretofore are not suitable for lapping dies having a range of tapers and aperture sizes. It is, therefore, another principal object of the invention to provide a lapping spindle construction better suited for use with dies having a range of aperture tapers and sizes.

The manner in which these and other objects are attained according to the invention will be described with reference to the accompanying drawings, wherein an embodiment of the invention is described.

In the drawings:

FIG. 1 is an elevation view of a spindle assembly with a lapping tool mounted thereon;

FIG. 2 is an axial cross-sectional view of the spindle assembly shown in FIG. 1;

FIG. 3 is a view on line 3-3 in FIG. 2;

FIG. 4 is a view taken along line 4-4 in FIG. 2;

FIG. 5 is an elevation view of the cam follower of the spindle assembly shown in FIG. 1 and FIG. 2; and

FIG. 6 is taken along line 66 in FIG. 5.

In the various views of the drawings, like reference characters refer to corresponding parts.

According to the invention, there is provided a lapping tool well suited for working apertured dies having different tapers and different size aperture openings. The lapping tool comprises a spindle assembly including a spindle, a cam pulley fixedly secured to the spindle and a cam follower in engagement with the cam surface of the cam pulley. The follower is adapted to follow the cam surface of the cam pulley and thereby define axial movement of the cam pulley and spindle. Spring means are provided for urging the cam surface into engagement with the cam follower and a feature of the invention is "ice provision of means for selectively adjusting spring tension of the spring means.

It has been found that provision of means to adjust the spring tension adapts the lapping tool for working dies of different taper and aperture sizes. Thus, when lapping a die with a relative small taper or aperture size, a lapping tool performs better when the spring tension is relatively small. Conversely, for a large taper or aperture size, high spring tension provides better results. Since the tool of the invention is adjustable with respect to spring tension, it is suited for lapping of small and large dies alike.

The invention also provides for lubrication of the cam engaging elements while at the same time protecting these elements from attack by abrasive dust particles. Thus, where the lapping tool is arranged so that the spindle is disposed vertically, the cam follower can include a roller rotatably mounted on the cam follower and arranged for rolling engagement with the cam surface of the cam pulley. The cam pulley and follower will be arranged in overlying relation with the roller interposed therebetween. The roller requires lubrication, and, hence will normally be wet so that it will pick up abrasive dust particles which are. prevalent in the environment of the lapping tool. This condition results in excessive wear of the cam elements and to obviate the difficulty, the spindle assembly of the invention provides an arrangement whereby the roller is flooded with oil maintained in a reservoir substantially protected from the dust laden environment of the tool and defined by an inner and outer wall which each extend axially upwardly from the cam follower or cam pulley, whichever is-the lowermost, and to-above the level of the roller. Protection for the oil from the dust laden environment is provided by disposing and shaping the walls so that but a small passage is present between the oil in the reservoir and the surrounding environment.

The lapping tool shown in the drawing comprises a spindle assembly including a vertically disposed spindle 11 mounted on a bench 1*2. Provision is made for imparting a combined rotating motion and reciprocating motion to the spindle, the means for importing such motions being the cam follower pulley 13 and cam pulley 14 and certain other parts shortly to be described. A pistoncylinder combination 15 is disposed between the ends of the spindle so as to be concentric therewith, the cylinder 16 being fixedly secured to the bench 12 by set screw 17, and the piston 18 being fixedly secured to the spindle 11. Axial movement of the spindle moves the piston axially of the cylinder and the piston-cylinder combination assures accurate alignment of the spindle during reciprocation and rotation thereof.

The cylinder 16 is formed by side wall 19, and lower and upper end walls 21 and 22 respectively. The said end walls being secured in place on the sidewall by screws 23. The upper and lower end walls, respectively, are provided with oversize openings 24 and 26 for the spindle 11 and in order to vent the inside of the cylinder; The piston is similarly formed and includes side wall 28, lower end wall 29 and upper end wall 31. Ball bearing units 32 and 33 are disposed within the piston and are operatively mounted between the piston and spindle so that the spindle is free to rotate in the piston.

On the lower end of the spindle 11 there'is provided a chuck 34 adapted for receiving a lapping tool 35. A locking nut 36 is provided for securing the chuck in place.

On the upper end of the spindle 11, there is mounted a thrust fitting 37 which includes a rotating member 38 secured to the spindle for rotation therewith by set screw 39, and a stationary member 41 disposed axially outward of the rotating member 38. A ball bearing unit 42 is operatively interposed between the rotating member 38 and stationary member 41 so that the rotating member is free to rotate with the spindle while the stationary member can be maintained in a fixed position.

According to the invention, means are provided for imposing thrust on the spindle during rotation thereof and for adjusting the magnitude of the thrust. Thus, the assembly includes cross-arm 46 having a pivot end 47 which is pivotally connected to the cross-arm keeper 48 in the form of a lug 49 secured to a shaft 51 which in turn is secured to the upper end wall 22 of cylinder 16. The cross-arm has an intraends portion 52 which resides in a slot 53 (see FIG. 4) formed in the thrust fitting stationary member 41. The end 54 of the cross-arm opposite the pivot end 47 is connected to a spring 56 which is elfective to urge the cross-arm toward the thrust fitting stationary member. One end of the spring is secured to post 57 which is mounted on the cylinder upper end wall 22, and the other end is connected to a link 58 having teeth 59. The teeth 59 are formed so as to engage a pin 61 secured to the spring loaded end 54 of the cross-arm 46. As will be apparent from the drawing, tension of the spring can be adjusted by manually changing the tooth of the toothed link 58, which engages the pin 61. An operating handle 62 is provided to facilitate making the adjustment. To facilitate the co-action of the cross'arm 46 and the thrust fitting 37 the lower wall 55 of the stationary fitting slot 53 (FIG. 4) is formed vu'th a convex contour, whereby the cross-arm is able to rock in the slot in accommodation of the reciprocation of the spindle.

The cam pulley 14 is fixedly secured to the spindle 11 by set screws 66, and has a skirt 67 extending axially of the spindle and terminating in a contoured cam surface 68 of changing elevation with respect to the lapping tool end of the spindle. See FIG. 4, FIG. and FIG. 6. The cam follower pulley 13 is mounted on the spindle concentric therewith and in the manner that it is rotatable with respect to the spindle. This mounting is described hereinafter. The pulley includes a cam follower in the form of two rollers 69 and 70, which are freely rotatably mounted on shafts 71 and 72, respectively, these shafts being secured to the cam follower pulley 13 by screws 73 and 74, respectively. The rollers are disposed to engage the cam surface 63 of the cam pulley 14 so as to follow the cam surface and define axial movement of the cam pulley and spindle.

It will be observed that the cam surface 68 of the cam pulley has two high points, which are shown resting on the rollers 69 and 70 in FIG. 2, and that as the cam pulley 14 is rotated relative to the cam follower pulley 13, the cam pulley 14 will reciprocate relative to the roller pulley 13. The cam pulley is secured to the spindle and its rotating and reciprocating motion is imparted to the spindle. The cam follower pulley, on the other hand, is not secured to the spindle and hence is not influenced by the action of the spindle.

The cam follower pulley 13 is mounted on the upper end wall 22 of the cylinder 16 so as to be freely rotatable. Ball bearing unit 77 is interposed between the roller pulley and cylinder end wall 22. The cam follower pulley is rotatable with respect to the spindle 11. Bearing sleeve 78 is interposed between the cam follower pulley 13 and spindle 11. The sleeve 78 rotates with the cam follower pulley and suitable lubrication of the sleeve is provided for by way of duct 79 which communicates at its upper end with oil hole 81, and at its lower end with the sleevespindle interface by way of oil hole 82.

For operation of the spindle assembly, V-belts 83 and 84 are provided for cam follower pulley 13 and cam pulley 14, respectively, and these V-belts are driven, respectively, by drive pulleys 86 and 87 which are mounted on drive shaft 83 of a constant speed motor (not shown). The cam follower pulley is of larger diameter than the cam pulley, the drive pulleys are of the same diameter, and hence the cam pulley rotates at a higher r.p.m., e.g., 200 rpm. higher, than the cam follower pulley. The rotation of the cam pulley 14 determines the rotation of the spindle 11 and the difference in rpm. between the cam pulley and cam follower pulley determines reciprocation of the spindle. A lapping tool 35 having an axially outwardly extending taper is mounted on the spindle and, as is shown in FIG. 1, is disposed for lapping a tapered die 91. The die 91 is secured in work holder 92. Abrasive for the lapping is contained in the cup 93. The rotation and reciprocation of the lapping tool provides the desired lapping action and feeding of abrasive to the work. The means for imposing thrust on the spindle, including the thrust fitting 37, cross-arm 46 and spring 56, permit adjustment of the tool to obtain the optimum lapping effect for the work conditions including die aperture size and taper, the type of material forming the die and the type of abrasive used.

To provide lubrication for the rollers 69 and 70 of the cam follower pulley 13, there is provided an oil reservoir 96 (see FIG. 4) wherein a body of oil is contained so that the rollers are flooded and the oil is relatively inaccessible to the environment of the spindle assembly which is laden with abrasive dust particles. The cam follower pulley 13 is provided with an outer oil retaining wall 97 which is fixedly mounted on the cam follower pulley at 98 and extends upwardly to above the level of the rollers 69 and 70. The top portion 99 of the outer retaining wall turns inwardly and extends to adjacent the skirt 67 depending from the cam pulley 14. Thus, a relatively small passageway 101 (FIG. 2) is disposed between the reservoir and the dust laden environment and hence very little dust finds its way into the reservoir. The inner oil retaining wall is the sleeve bearing 78 and this also extends to above the level of the rollers.

Whereas a particular embodiment of the invention has been described in detail, the invention includes various alternatives, modification and equivalents. Substitution can be made for the rollers of the cam follower pulley, other constructions can be employed for urging the cam pulley and cam follower pulley into engagement and various of the parts can be reversed such as the cam pulley being made rotatable with respect to the spindle and the cam follower pulley being fixedly mounted on the shaft instead of vice versa as is shown in the drawings.

What is claimed is:

1. A spindle assembly for a lapping tool comprising a vertically disposed spindle having means for securing a lapping tool to one end thereof and a thrust fitting secured to the other end thereof, a cam pulley fixedly secured to the spindle and including a skirt extending axially of the spindle and terminating in a cam surface of changing elevation with respect to the lapping tool end of the spindle, a cam follower pulley concentric with the spindle and including a cam follower in engagement with the cam surface of the cam pulley for following the cam surface and defining axial movement of the cam pulley and spindle, said cam follower being disposed between the cam pulley and lapping tool end of the spindle at a fixed elevation, means for rotating said pulleys at different r.p.m.s, whereby the cam pulley can be rotated with respect to the cam follower and reciprocating and rotary motion can be imported to the spindle, a piston-cylinder combination between the ends of the spindle concentric therewith, the cylinder being fixedly positioned and the spindle being secured to the piston, whereby axial movement of the spindle moves the piston axially of the cylinder and accurate alignment of the spindle is maintained upon reciprocation and rotation of the spindle, said thrust fitting including a rotating member secured to the spindle for rotation therewith and a stationary member disposed axially outward of the rotating member, said assembly further including a cross-arm having one end thereof pivotally secured to a fixedly positioned cross-aim keeper, an intraends portion thereof bearing on the thrust fitting stationary member and the other end thereof connected to a spring effective to urge the crossarm toward the thrust fitting stationary member, whereby thrust is imposed on the spindle to press the cam surface into tight engagement with the cam follower, and means for adjusting the tension of the spring.

2. In combination a spindle assembly according to claim 1, and a lapping tool secured to the lapping tool end of the spindle, said lapping having an axially outwardly extending taper.

3. A spindle assembly according to claim 1, the 0am follower of the cam follower pulley being a roller rotatably mounted on the cam follower pulley for rolling engagement with the cam surface of the cam pulley.

4. A spindle assembly according to claim 3, said cam follower pulley including an outer oil retaining wall dis- References Cited in the file of this patent UNITED STATES PATENTS 1,530,058 Ranagan Mar. 17, 1925 1,952,653 Brown Mar. 27, 1934 2,242,781 Gideon May 20, 1941 

